`A B C D` is a cyclic quadrilateral such that `/_A D B=30^0a n d\ /_D C A=80^0,` the `/_D A B=` `70^0` (b) `100^0` (c) `125^0` (d) `150^0`

Explanation

`/_ADB=30^0
\and\ /_DCA=80^0`
Now,
`/_DCA=/_DBA=80^0`(Angle subtended by same chord are equal).
In `/_\ADB,
/_ADB+/_DBA+/_DAB=180^0`
(Sum of angles in triangle is `180^0)`
`/_DAB=180^0−80^0−30^0=70^0`
Hence, the measure of `/_DAB \is\ 70^0.`
Therefore, option A is correct.